There are many different individual tests and signs described in the knee and for most of these the sensitivity and specificity has not been adequately reported. Surgeons therefore tend to have a set of primary signs or findings that confirm a particular diagnosis backed up by a set of secondary or confirmatory signs. For example a ‘full house’ of findings for a torn meniscus is a history of a twisting injury, knee effusion (current or history of) and specific deep tenderness on the postero-medial joint line. In the absence of a ‘full house’ then confirmatory examination is indicated including McMurray’s test, squat duck walking, or palpation in the figure 4 position.
This observation leads on to other points. The full house mentioned above assumes that the patient is in the right broad age group category for the specific diagnosis of meniscal injury and that the diagnosis will lead to an appropriate treatment. It should be remembered that the purpose of history and examination is to lead to a diagnosis that results in a management plan that hopefully leads to patient benefit. This might mean for example sometimes all that is required is a decision whether a patient needs an arthroscopy or not, based on mechanical symptoms, where reaching a specific diagnosis may not be required. Knee examination and radiographs might, for example, show a severely arthritic knee but if the patient has only mild pain then arthroplasty is unlikely to be indicated. Again, history and examination are targeted towards a diagnosis leading to management decisions.
To achieve this, we note that knee problems will present with various characteristic patterns that will lead to the patient being categorised in to a diagnostic box. Specific direct questions may be needed to aid this process. This is not asking ‘leading questions’ but ‘direct questioning’ that helps focus the patients mind onto the specific symptoms and the examiner onto specific possible diagnoses. For example to detect ACL deficiency the specific question ‘do you trust your knee?’ or ‘did you hear a pop at the time of injury?’ may need to be asked to lead to that diagnosis.